WARNING: This page is about a different car, the 2002 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
Install the drive belt tensioner.
Install the drive belt tensioner nut.
Tighten:
Tighten the nut to 50 N.m (37 lb ft)
Fig 1: Drive Belt Tensioner Installation - Left (L67)